Is my app really using uvloop?

[jwoehr]

I installed uvloop in the virt env of an extant application and changed loop in the uvicorn.Config to "uvloop".
However, one time I have gotten a timeout error raised on a very slow machine and it comes from h11/_writers.py.
Afterwards, loading the same page, everything is fine.
But it made me wonder if uvloop is actually being used.
Is there a way to determine if the code is running uvloop? Printing out the config shows 'loop': 'uvloop'.
Full stack trace:

ERROR:    Exception in ASGI application
Traceback (most recent call last):
  File "/home/JWOEHR/myvenv/lib/python3.9/site-packages/uvicorn/protocols/http/h11_impl.py", line 408, in run_asgi
    result = await app(  # type: ignore[func-returns-value]
  File "/home/JWOEHR/myvenv/lib/python3.9/site-packages/uvicorn/middleware/proxy_headers.py", line 84, in __call__
    return await self.app(scope, receive, send)
  File "/home/JWOEHR/myvenv/lib/python3.9/site-packages/quart/app.py", line 1902, in __call__
    await self.asgi_app(scope, receive, send)
  File "/home/JWOEHR/myvenv/lib/python3.9/site-packages/quart/app.py", line 1928, in asgi_app
    await asgi_handler(receive, send)
  File "/home/JWOEHR/myvenv/lib/python3.9/site-packages/quart/asgi.py", line 51, in __call__
    _raise_exceptions(done)
  File "/home/JWOEHR/myvenv/lib/python3.9/site-packages/quart/asgi.py", line 353, in _raise_exceptions
    raise task.exception()
  File "/home/JWOEHR/myvenv/lib/python3.9/site-packages/quart/asgi.py", line 102, in handle_request
    await asyncio.wait_for(self._send_response(send, response), timeout=timeout)
  File "/QOpenSys/pkgs/lib/python3.9/asyncio/tasks.py", line 479, in wait_for
    return fut.result()
  File "/home/JWOEHR/myvenv/lib/python3.9/site-packages/quart/asgi.py", line 133, in _send_response
    await send(
  File "/home/JWOEHR/myvenv/lib/python3.9/site-packages/uvicorn/protocols/http/h11_impl.py", line 505, in send
    output = self.conn.send(event=h11.Data(data=data))
  File "/home/JWOEHR/myvenv/lib/python3.9/site-packages/h11/_connection.py", line 512, in send
    data_list = self.send_with_data_passthrough(event)
  File "/home/JWOEHR/myvenv/lib/python3.9/site-packages/h11/_connection.py", line 545, in send_with_data_passthrough
    writer(event, data_list.append)
  File "/home/JWOEHR/myvenv/lib/python3.9/site-packages/h11/_writers.py", line 65, in __call__
    self.send_data(event.data, write)
  File "/home/JWOEHR/myvenv/lib/python3.9/site-packages/h11/_writers.py", line 91, in send_data
    raise LocalProtocolError("Too much data for declared Content-Length")
h11._util.LocalProtocolError: Too much data for declared Content-Length

[zanieb]

You could check if the current event loop (https://docs.python.org/3/library/asyncio-eventloop.html#asyncio.get_running_loop) is the one injected by uvloop (https://github.com/MagicStack/uvloop/blob/master/uvloop/__init__.py#L18-L20)

[jwoehr]

Thank you @zanieb I will explore this.